In electrical wire or cable stringing applications, such as situations where wire is pulled through a conduit by a cable or line at a desired and controlled rate, there is a need for the pulling cable line to be supported under tension by use of some form of a cable support device such as a drum or spool. In cable laying operations the heavy electrical or mechanical cable to be pulled under tension through support conduits or over utility poles is in conventional practice hooked up to some kind of "fish wire" or "pulling line" attached to the leading end of the cable. In operation, the pulling line pulls the heavy cable through the conduit or over the poles until it is in the desired position. The pulling action is generally accomplished through a cable support drum or capstan which is rotatable.
The drum provides an anchoring surface on which the pulling line may be wound so as to utilize the rotational motion of the drum toward imparting pulling action on the cable. Under such conditions, forces are generated which accumulate and tend to collapse the drum or spool onto which the pulling line is being wound. Such collapsing generally occurs as a result of the cumulative effects of tension generated during the pulling action. One such effect is the direct result of the cable being under tension while it is actually being pulled by the pulling line. Another factor is the force existing due to the weight of the cable itself, which can amount to a significant value depending upon the particular cable winding application. The weight of the cable adds considerably to the operating tension particularly when the pulling line is utilized for lifting heavy cable through large distances in vertical conduits or poles, against gravitational forces. Another source of increased pulling force is the angle between the cable and the capstan. Because of this angle, the total force exerted on the cable has to be greater in order to provide a sufficient force component in a direction parallel to the capstan.
Since the surface of the drum onto which the pulling line is wound is the effective fulcrum of support, it is subjected to all the accumulated forces resulting from the tension generated as the pulling line is progressively wound or unwound around the support drum. Such accumulated forces of tension tend to collapse the drum or spool during the cable pulling operation. This collapsing effect of the tensioning forces is compounded when the cable pulling operation requires intermittent "pulling" and "braking" actions of the pulling line, which frequently is the case. In the past, this problem has been solved, among other ways, by the use of winding drums or spools made of heavy duty material capable of withstanding the compressive forces generated during high tension winding.
One solution to this problem is provided by Applicant's prior take-up system disclosed in U.S. Pat. No. 4,657,202. A reel assembly for playing out the cable is disclosed in Applicant's U.S. Pat. No. 4,325,522. Heavy duty capstans also have been utilized, but then the cable pulling line generally merely is played out onto the ground for later rewinding.
It would be desirable to provide a take-up spool which can be utilized in conjunction with a capstan, which take-up spool does not need to withstand the high forces transmitted to the capstan, and which will level wind the cable pulling line around the take-up spool for reuse.
It would be desirable if the take-up spool included a means for preventing spill of the wound cable pulling line when the motor is inoperative or being reverse driven.
It would further be desirable to optionally allow the entire winding assembly, or a subassembly thereof, to be movable so as to reduce or eliminate large angular differences between the capstan position and the approach of cable being reeled in.